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author | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
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committer | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
commit | 5f8de423f190bbb79a62f804151bc24824fa32d8 (patch) | |
tree | 10027f336435511475e392454359edea8e25895d /security/nss/lib/freebl/mpi/utils/fact.c | |
parent | 49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff) | |
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Add m-esr52 at 52.6.0
Diffstat (limited to 'security/nss/lib/freebl/mpi/utils/fact.c')
-rw-r--r-- | security/nss/lib/freebl/mpi/utils/fact.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/security/nss/lib/freebl/mpi/utils/fact.c b/security/nss/lib/freebl/mpi/utils/fact.c new file mode 100644 index 000000000..da8e61a32 --- /dev/null +++ b/security/nss/lib/freebl/mpi/utils/fact.c @@ -0,0 +1,84 @@ +/* + * fact.c + * + * Compute factorial of input integer + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "mpi.h" + +mp_err mp_fact(mp_int *a, mp_int *b); + +int +main(int argc, char *argv[]) +{ + mp_int a; + mp_err res; + + if (argc < 2) { + fprintf(stderr, "Usage: %s <number>\n", argv[0]); + return 1; + } + + mp_init(&a); + mp_read_radix(&a, argv[1], 10); + + if ((res = mp_fact(&a, &a)) != MP_OKAY) { + fprintf(stderr, "%s: error: %s\n", argv[0], + mp_strerror(res)); + mp_clear(&a); + return 1; + } + + { + char *buf; + int len; + + len = mp_radix_size(&a, 10); + buf = malloc(len); + mp_todecimal(&a, buf); + + puts(buf); + + free(buf); + } + + mp_clear(&a); + return 0; +} + +mp_err +mp_fact(mp_int *a, mp_int *b) +{ + mp_int ix, s; + mp_err res = MP_OKAY; + + if (mp_cmp_z(a) < 0) + return MP_UNDEF; + + mp_init(&s); + mp_add_d(&s, 1, &s); /* s = 1 */ + mp_init(&ix); + mp_add_d(&ix, 1, &ix); /* ix = 1 */ + + for (/* */; mp_cmp(&ix, a) <= 0; mp_add_d(&ix, 1, &ix)) { + if ((res = mp_mul(&s, &ix, &s)) != MP_OKAY) + break; + } + + mp_clear(&ix); + + /* Copy out results if we got them */ + if (res == MP_OKAY) + mp_copy(&s, b); + + mp_clear(&s); + + return res; +} |